System and method for moving a rod of build material using a pusher in a 3D printing system

ABSTRACT

A system and corresponding method to move a rod of build material in a three-dimensional (3D) printing system uses a pusher. The rod of build material has distal and proximal ends relative to an extrusion head. The distal and proximal ends having distal and proximal end surfaces, respectively. The pusher engages with the rod and applies an axial force to at least a portion of the distal end surface of the rod for at least a portion of a path the rod travels toward the extrusion head. The axial force actuates the rod of build material without alteration, such as by shaving, fracturing, or otherwise deforming the rod of build material.

RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.15/961,817, filed on Apr. 24, 2018, which claims the benefit of U.S.Provisional Application No. 62/489,306, filed on Apr. 24, 2017. Theentire teachings of the above applications are incorporated herein byreference.

BACKGROUND

Fused filament fabrication (FFF) provides a technique for fabricatingthree-dimensional (3D) objects from a thermoplastic or from similarmaterials. Machines using this technique can fabricate a 3D object,additively, by depositing materials in layers to build up a physicalobject, additively, layer-by-layer, based on a computer model of the 3Dobject.

SUMMARY

According to an example embodiment, an extrusion assembly for use in athree-dimensional (3D) printing system may include an extrusion headconfigured to receive a rod of build material having distal and proximalends relative to the extrusion head, the distal and proximal ends havingdistal and proximal end surfaces, respectively. The extrusion assemblymay include an actuation assembly including a pusher, the pusherarranged to apply an axial force to at least a portion of the distal endsurface of the distal end of the rod. The axial force may be applied tothe at least a portion of the distal end surface for at least a portionof a path the rod travels toward the extrusion head.

The distal end surface may be a normal surface or feature that is normalrelative to a longitudinal axis of the rod of build material.

The actuation assembly may further include an actuating componentcoupled to the pusher and a driving component coupled to the actuatingcomponent. The driving component may be configured to drive theactuating component in a manner that causes bi-directional linear motionof the pusher relative to the extrusion head. The axial force may beapplied as a function of the pusher being caused to move, linearly,toward the extrusion head.

The actuating component may be a lead screw and the driving componentmay be a motor.

The actuation assembly may further include an actuating component. Thepusher may include a traveling component and a pushing component. Thetraveling component may be arranged to travel, linearly, along a linearactuation path defined by the actuating component, to cause linearmotion of the pushing component.

The pusher may include a pusher interface and the pusher interface maybe arranged to engage with the at least a portion of the distal endsurface.

The pusher interface may include complementary features relative tosurface features of the at least a portion of the distal end surface ofthe rod of build material.

The pusher may include a traveling component and a pushing component andthe pushing component may include at least one cantilevered protrusionof the traveling component.

The pusher may include a traveling component arranged to cause motion ofthe pusher. The traveling component may be a nut.

The pusher may include a traveling component. The actuation assembly mayfurther include an actuating component arranged to move the travelingcomponent and a linear guide coupled to the traveling component via alinear bearing. The linear guide and the linear bearing may be arrangedto absorb a load otherwise transferred to the actuating component due toapplication of the axial force.

The linear guide may be a linear rail.

The extrusion assembly may further comprise a guide channel. The pushermay include a pushing component. The at least a portion of the path therod travels toward the extrusion head may be defined by the guidechannel. The guide channel may be define at least one slot to receivethe pushing component.

The guide channel may be arranged to contact at least a portion of therod of build material to provide alignment for the at least a portion ofthe rod.

The pusher may include a pushing component. The actuation assembly mayfurther include a cam arranged to cause the pushing component totransition between a media load position and a media extrude position asa function of surface contact between the cam and the pushing component.

In the media load position, the pushing component may be arranged to beout of the path the rod travels toward the extrusion head. In the mediaextrude position, at least a portion of the pushing component may bearranged to be in the path the rod travels toward the extrusion head.

The extrusion assembly may include a media entrance arranged to load therod of build material into the extrusion assembly. The path the rodtravels toward the extrusion head may be from the media entrance to theextrusion head.

According to another example embodiment, a method for moving a rod ofbuild material in a three-dimensional (3D) printing system may compriseengaging a rod of build material, loaded into an extrusion assemblyincluding an extrusion head, with a pusher, the rod having distal andproximal ends relative to the extrusion head, the distal and proximalends having distal and proximal end surfaces, respectively. The methodmay comprise applying an axial force to at least a portion of the distalend surface of the distal end of the rod. The axial force may beapplied, by the pusher, to the at least a portion of the distal endsurface for at least a portion of a path the rod travels toward theextrusion head in the 3D printing system.

The method may comprise driving an actuating component to cause thepusher to move between a home location and a reset location within theextrusion assembly. The home location and the reset location may bedistal and proximal pusher locations, respectively, of the pusherrelative to the extrusion head. The method may comprise sensing whetherthe pusher is located at the home and reset locations.

The sensing may be based on feedback from a sensing device.

The sensing may be performed in an open-loop manner as a function of atheoretical commanded location.

The rod of build material may be a first rod of build material and themethod may further comprise driving the actuating component in a mannerthat causes the pusher to move from the reset location to the homelocation in response to the reset location being sensed. The method mayfurther comprise loading a second rod of build material into theextrusion assembly in response to the home location being sensed.

The pusher may include a traveling component and a pushing component.The method may further comprise moving the pushing component between amedia load position and an extrusion position. The media load positionmay be employed for loading the rod of build material and the extrusionposition may be employed for extruding the rod of build material.

The pusher may include a traveling component and a pushing component.The method may further comprise driving an actuating component coupledto the traveling component. The driving may cause rotation of theactuating component that, in turn, may cause linear motion of thepusher.

The linear motion may include a first linear motion toward the extrusionhead and a second linear motion away from the extrusion head and theapplying may include driving the actuating component in a manner thatcauses the second linear motion.

The method may further comprise loading the rod of build material into aguide channel. The guide channel may define the at least a portion ofthe path the rod travels toward the extrusion head.

The method may further comprise contacting a rod surface of the rod withat least a portion of an inner surface of the guide channel. Thecontacting may cause the rod to be aligned within the guide channel.

The pusher may include a traveling component and a pushing component andthe method may further comprise loading the rod of build material into aguide channel, the guide channel defining at least one slot; driving anactuating component coupled to the traveling component; traversing theactuating component with the traveling component in a first directionaway from the extrusion head in response to the driving; and traversinga given slot of the at least one slot with the pushing component in asecond direction toward the extrusion head to apply the axial force inresponse to the traversing of the actuating component in the firstdirection.

According to another example embodiment, an actuation system for use ina three-dimensional (3D) printing system may comprise a pusher; anactuating component coupled to the pusher; a driving componentconfigured to drive the actuating component; and a controller. Thecontroller may be configured to cause the driving component to drive theactuating component to move in a manner that causes the pusher to applyan axial force to at least a portion of a distal end surface of a distalend of a rod of a build material. The rod may have distal and proximalends relative to an extrusion head. The distal and proximal ends mayhave distal and proximal end surfaces, respectively. The axial force maybe applied to the at least a portion of the distal end surface of therod for at least a portion of a path the rod travels toward theextrusion head in the 3D printing system.

According to another example embodiment, an apparatus for moving a rodof build material in a three-dimensional (3D) printing system maycomprise means for engaging a rod of build material having distal andproximal ends relative to an extrusion head, the distal and proximalends having distal and proximal end surfaces, respectively; and meansfor applying an axial force to at least a portion of the distal endsurface of the distal end of the rod. The axial force may be applied tothe at least a portion of the cross-sectional surface for at least aportion of a path the rod travels toward the extrusion head.

According to an example embodiment, an extrusion assembly for use in athree-dimensional (3D) printing system may include an extrusion headconfigured to receive a build material and an actuation assembly. Theactuation assembly may include an actuating component and a gripper. Thegripper may be arranged to apply at least two opposing lateral forces tothe build material, the at least two opposing lateral forces beingapplied to the build material for at least a portion of a path the buildmaterial travels toward the extrusion head. The actuating component maybe arranged to cause linear motion of the gripper for the at least aportion of the path.

The actuation assembly may further include a gripper guide, the gripperguide arranged to cause the gripper to apply the at least two opposinglateral forces.

The actuation assembly may further include a spring arranged to causethe gripper guide to move in a direction away from the extrusion headand toward a home position for the gripper guide within the actuationassembly.

The extrusion assembly may include an extrusion frame arranged to housethe gripper, a gripper guide for the gripper, and a spring.

The extrusion frame may define a stopping ledge within the frame, thestopping ledge arranged to stop movement of the gripper guide in adirection away from the extrusion head. The stopping ledge may define ahome position for the gripping guide and the gripper.

The extrusion assembly may further comprise a traveling component. Thegripper may be coupled to the traveling component and the actuationassembly may further include: a gripper guide arranged to cause thegripper to dilate and contract within the gripper guide and a drivingcomponent configured to drive the actuating component to cause thetraveling component to move bi-directionally relative to the extrusionhead.

The extrusion assembly may further comprise a traveling component. Thetraveling component may define a hollow core configured to enable thebuild material to pass through the traveling component and toward theextrusion head.

The build material may be in a form of a discrete rod or continuousfeedstock.

The gripper may be arranged to apply the at least two lateral forces viavacuum.

The actuation assembly may further comprise a first belt and a secondbelt and the build material may be arranged between surfaces of thefirst belt and second belts.

The gripper may be coupled to the first belt and the second belt andarranged to apply the at least two lateral forces to the build materialvia the first and second belts.

The gripper may include: a linear element; a first rolling element; asecond rolling element; a first gripping element; and a second grippingelement. The linear element may be coupled to the first and secondgripping elements and at least two rolling elements.

The extrusion assembly may further comprise a linear guide and thegripper may be arranged to travel the linear guide.

According to another example embodiment, a method for moving buildmaterial in a three-dimensional (3D) printing system may compriseapplying at least two opposing lateral forces to a build material via agripper, the at least two opposing lateral forces being applied to thebuild material for at least a portion of a path the build materialtravels toward an extrusion head. The method may comprise causing linearmotion of the gripper for the at least a portion of the path the buildmaterial travels toward the extrusion head.

The linear motion of the gripper may cause the gripper to enter agripper guide and the method may further comprise compressing anddilating the gripper via a profile of an internal surface of the guide.

The applying may include driving an actuating component in a manner thatcauses opposing surfaces of the gripper to engage with opposing surfacesof the build material via respective couplings and wherein the linearmotion of the gripper causes rotation of the respective couplings.

The respective couplings may be belts.

An actuation system for use in a three-dimensional (3D) printing systemmay comprise a gripper coupled to a traveling component; an actuatingcomponent coupled to the traveling component; a driving componentconfigured to drive the actuating component; and a controller configuredto activate and deactivate the driving component.

The driving component may be further configured to drive the actuatingcomponent to cause the traveling component to move bi-directionallyrelative to an extrusion head.

According to an example embodiment, an apparatus for moving buildmaterial in a three-dimensional (3D) printing system may comprise meansfor applying at least two opposing lateral forces to the build material,the at least two opposing lateral forces being applied to the buildmaterial for at least a portion of a path the build material travelstoward the extrusion head; and means for causing linear motionconcurrent, with engagement of the build material, for the at least aportion of the path the build material travels toward the extrusion headin the 3D printing system.

It should be understood that example embodiments disclosed herein can beimplemented in the form of a method, apparatus, system, or computerreadable medium with program codes embodied thereon.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

The foregoing will be apparent from the following more particulardescription of example embodiments, as illustrated in the accompanyingdrawings in which like reference characters refer to the same partsthroughout the different views. The drawings are not necessarily toscale, emphasis instead being placed upon illustrating embodiments.

FIG. 1 is a block diagram of an example embodiment of athree-dimensional (3D) printing system.

FIG. 2A is computer-aided design (CAD) drawing of an extrusion assemblyfor use in a 3D printing system.

FIG. 2B is a block diagram of an example embodiment of a distal endsurface of a rod of build material.

FIG. 2C is a block diagram of another example embodiment of the distalend surface of the rod of build material.

FIG. 2D is a block diagram of an example embodiment of a 3D coordinatesystem and the axial force.

FIG. 2E is a CAD drawing of a cross-sectional view of an exampleembodiment of the extrusion assembly of FIG. 2A.

FIG. 2F is a CAD drawing of another example embodiment of the extrusionassembly of FIG. 2A.

FIG. 2G is a CAD drawing of an example embodiment of the pushingcomponent of FIG. 2F in a passive position to enable media loading.

FIG. 2H is a CAD drawing of an example embodiment of the pushingcomponent of FIG. 2F in an active position for extruding media.

FIG. 2I is a CAD drawing of a cross-sectional view of an exampleembodiment of the cam of FIG. 2F.

FIG. 2J is a block diagram of an example embodiment of a path a rod ofbuild material travels toward the extrusion head.

FIG. 3A is a CAD drawing of an example embodiment of a portion of anextrusion assembly.

FIG. 3B is a CAD drawing of a cross-sectional view of the exampleembodiment of FIG. 3A, disclosed above, that includes a guide channel.

FIG. 3C is a CAD drawing of an isometric view of the pusher of FIG. 3Adisclosed above.

FIG. 3D is a CAD drawing of another isometric view of the pusher of FIG.3A disclosed above.

FIG. 4A is an isometric view of an example embodiment of an actuationassembly that includes a linear rail and geared flipper.

FIG. 4B is a cross sectional view of the example embodiment of theactuation assembly of FIG. 4A.

FIG. 5 is a flow diagram of an example embodiment of a method for movinga rod of build material in a three-dimensional (3D) printing system.

FIG. 6 is a block diagram of an example embodiment of an actuationsystem for use in a three-dimensional (3D) printing system.

FIG. 7 is a flow diagram of an example embodiment of another method formoving a rod of build material in a three-dimensional (3D) printingsystem.

FIG. 8 is a block diagram of an example embodiment of an actuationsystem that uses a gripper.

FIG. 9A is a cross sectional view of an example embodiment of anextrusion assembly that includes an actuation assembly in a start mode.

FIG. 9B is a cross sectional view of an example embodiment of theextrusion assembly of FIG. 9A with the actuation assembly transitionedto an extrusion mode.

FIG. 9C is a cross sectional view of an example embodiment of theextrusion assembly of FIG. 9A with the actuation assembly transitionedto a first media reload mode.

FIG. 9D is a cross sectional view of an example embodiment of theextrusion assembly of FIG. 9A with the actuation assembly transitionedto a second media reload mode.

FIG. 9E is a cross sectional view of an example embodiment of theextrusion assembly of FIG. 9A with the actuation assembly transitionedto a third media reload mode.

FIG. 10A is block diagram of an example embodiment of a gripper.

FIG. 10B is block diagram of an example embodiment the gripper of FIG.10A.

FIG. 11 is block diagram of another example embodiment of an actuationassembly that includes a gripper.

FIG. 12 is a block diagram of an example internal structure of acomputer in which various embodiments of the present disclosure may beimplemented.

DETAILED DESCRIPTION

A description of example embodiments follows.

Fused filament fabrication (FFF) provides a technique for fabricatingthree-dimensional (3D) objects from a thermoplastic or from similarmaterials. Machines using this technique can fabricate a 3D object,additively, by depositing materials in layers to build up a physicalobject, additively, layer-by-layer, based on a computer model of the 3Dobject. While these polymer-based techniques have been changed andimproved over the years, the physical principles applicable topolymer-based systems may not be applicable to metal-based systems,which tend to pose different challenges, as disclosed below.

In extrusion technologies for additive manufacturing, referred tointerchangeably herein as 3D printing or 3DP, printers often utilize apair of drive gears (with or without teeth) to actuate a thermoplasticfeedstock into a liquefying extruder. The drive gears engage the media,that is, the feedstock, which provides traction and enables transmissionof force to convert circular motion of the gears into a lineartranslation of the feedstock. Since the pressure to extrude the mediacan be quite large (e.g., exceeding 10 atmospheres), a large force isnecessarily imparted at the interface between a roller and thefeedstock. Such forces cause an elastic deformation of the media and mayadditionally lead to plastic deformation, fracture, and shaving, orslip/stripping of media on the rollers. Preventing and eliminatingslipping and stripping errors may be useful in ensuring a steady andpredictable extrusion of the manufacturing process.

A demand for printed structures composed of metals and ceramics with lowproduction times creates a need for high-speed printing of metal- andceramic-laden thermoplastic materials. These materials are moresusceptible to failure within the geared teeth roller design, disclosedabove, both by slipping and stripping, owing to their increasedbrittleness as compared to traditional 3D printing plastics. Metal rodsmay beneficially be used in 3D printing of metals, the rods being, forexample, several centimeters in length with a diameter of only a fewmillimeters. As such, the pressure to overcome extrusion forces due tothe diameter change may be quite large, as disclosed above. Further,ever-improving print quality demands features and parts with fine layerheights, and, as such, an increase in extrusion force while maintainingand decreasing the time used to print a complete part may be useful.

The roller-type extrusion design, disclosed above, may be consideredinsufficient to meet current and future performance demands since suchpressure may deform the material within such a design. Thus, an improvedmeans of actuation is useful in order to deliver the thermoplasticmaterial or metal feedstock to the printed part at a desired (i.e.,target) speed and consistency. According to an example embodiment forbuild material actuation, media may be pushed and/or gripped and pushedin a manner such that there is no relative motion between an actuatorand a point of contact on the feedstock, that is, the media.

Described herein are devices, systems, and methods related to 3Dprinting, where a design, such as a computer-aided drafting (CAD) file,is provided to a computer operably connected to a 3D printing system,such as a 3D metal printing system, and the 3D object represented by thedesign may be manufactured in a layer-by-layer fashion by the 3Dprinting system. In general, the following disclosure may emphasize 3Dprinting using metal as a build material for forming a 3D object. Morespecifically, the disclosure may emphasize metal 3D printing systemsthat may deposit metal, metal alloys, or other metallic compositions forforming a 3D object using fused filament fabrication or similartechniques.

FIG. 1 is a block diagram of an example embodiment of athree-dimensional (3D) printing system 100, that is, an additivemanufacturing system. The 3D system 100 may, for example, be a metallicprinting system that employs fused filament fabrication. The 3D printingsystem 100 may use metal build material, such as a metallic alloy orbulk metallic glass. However, the 3D printing system 100 may also orinstead be used with other build materials including plastics, ceramics,and the like, as well as combinations of the foregoing.

In general, the 3D printing system 100 may deposit a metal, metal alloy,metal composite or the like, using fused filament fabrication. The 3Dprinting system 100 includes an extrusion assembly 106 configured toreceive build material 104 that is propelled by an actuation assembly108 into an extrusion head 112 and heated to a workable state by heat116 generated by a heater 114, and then extruded through one or morenozzle(s) 113 to produce the workable build material 122. It should beunderstood that the heater 114 is an example for generating the heat 116and that the heat 116 may be generated in any suitable way, such as viafriction of the build material 104 interacting with the extrusionassembly 106. By concurrently controlling robotics (not shown) toposition the nozzle(s) 113 along an extrusion path relative to a buildplate 120, a 3D object 110 may be fabricated on the build plate 120within, for example, a build chamber (not shown), the build chamberhousing any suitable combination of devices or systems of the 3Dprinting system 100.

In general, a controller 118 may be configured to manage operation ofthe 3D printing system 100 to fabricate the 3D object 110 according to a3D model using a fused filament fabrication process or the like. Thecontroller 118 may be remote or local to the 3D printing system 100 andmay be a centralized or distributed system. The controller 118 may beconfigured to generate control signals, such as the feeder controlsignal(s) 103 a that may control a feeder assembly 102 to dispense thebuild material 104 or the extrusion control signal(s) 103 b that maycontrol the extrusion assembly 106 or elements included therein, such asthe actuation assembly 108, heater 114, extrusion head 112, nozzle(s)113, or any other suitable device or system for use in managing the 3Dprinting process.

Further, the controller 118 may receive status, such as the feederassembly status 105 a or extrusion status 105 b, received from thefeeder assembly 102 and the extrusion assembly 106, respectively, or anyother suitable status signal(s) from any other suitable device or systemfor use in managing the 3D printing process.

As disclosed above, an improved means of actuation is useful in order todeliver the build material 105, that may be a thermoplastic material ormetal feedstock, to the printed part, that is, the 3D object 100 at adesired (i.e., target) speed and consistency. As such, the 3D actuationassembly 108 has improved build material actuation, for example,relative to the roller-type design, disclosed above.

A linear actuator is an actuator that creates motion in a straight line,in contrast to circular motion of a conventional electric motor. Linearactuators are used in machine tools and industrial machinery, incomputer peripherals such as disk drives and printers, in valves anddampers, and in many other places where linear motion is useful.Hydraulic or pneumatic cylinders inherently produce linear motion. Manyother mechanisms may be used to generate linear motion from a rotatingmotor.

Typically, a roller-type design of drive gears engage the media andconvert circular motion of the gears into a linear translation of thefeedstock, such as the build material 104 of FIG. 1, disclosed above. Achief downside to employing a roller-type design for the drive gear isthe limited engagement area of the actuator with the feedstock. Toresolve this, an example embodiment of the actuation assembly 108 mayemploy linear actuation to push, and/or grip and push the build material104, such that there is no relative motion between the actuator and apoint of contact on the feedstock. Further, an example embodiment mayenable reloading such that extrusion can operate semi-continuously andwithout manual reloading and resetting operations. An example embodimentmay move a rod of build material, that is, a discrete element of thebuild material 104, in the 3D printing system 100 using a pusher, suchas the pusher 242 of FIG. 2A, disclosed below.

FIG. 2A is a computer-aided design (CAD) drawing of an extrusionassembly 206 for use in a 3D printing system, such as the 3D printingsystem 100 of FIG. 1, disclosed above. The extrusion assembly 206includes an extrusion head 212 configured to receive a rod of buildmaterial 204 having distal and proximal ends relative to the extrusionhead 212, that is, the distal end 232 and the proximal end 234. Thedistal and proximal ends having distal and proximal end surfaces,respectively, such as the distal end surface 233 and the proximal endsurface 231. The extrusion assembly 206 includes an actuation assembly208 that includes the pusher 242. The pusher 242 is arranged to apply anaxial force 235 to at least a portion of the distal end surface of thedistal end 232 of the rod of build material 204. The axial force 235 isapplied to the at least a portion of the distal end surface for at leasta portion of a path the rod travels toward the extrusion head 212.According to an example embodiment, the distal end surface may be anormal surface or feature that is normal relative to a longitudinal axisof the rod of build material. The at least a portion of the path may bea portion of an extrusion path, such as the extrusion path 238 disclosedbelow with regard to FIG. 2J. The axial force 235 actuates the rod ofbuild material without alteration, such as by shaving, fracturing, orotherwise deforming the rod of build material 204. The axial force 235is sufficient to overcome extrusion forces due to a diameter changebetween the rod of build material 204 and the nozzle tip 215 of thenozzle 213.

The extrusion head 212 includes a cold end 256 and a hot end 258.According to the example embodiment, the extrusion assembly 206 includesheating elements 214 a and 214 b that may be configured to generate heatto transform the rod of build material 204 to the workable buildmaterial 222.

The actuation assembly 208 may further include an actuating component248 coupled to the pusher 242 and a driving component 252 coupled to theactuating component 248. The driving component 252 may be configured todrive the actuating component 248 in a manner that causes bi-directionallinear motion of the pusher 242 relative to the extrusion head 212. Theaxial force 235 may be applied as a function of the pusher 242 beingcaused to move, linearly, toward the extrusion head 212.

According to an example embodiment, the actuating component 248 may be alead screw and the driving component 252 may be a motor. However, theactuation component 248 may be any suitable actuating component that maybe driven to cause the pusher 242 to move in a bi-directional motionrelative to the extrusion head 212. Further, the driving component 252need not be a motor and may be any suitable mechanical, pneumatic,electro-mechanical, magnetic, or other type of driving component fordriving the actuating component 248 to cause linear motion of the pusher242.

The pusher 242 includes a traveling component 244 and a pushingcomponent 246. The pushing component 246 may be arranged to be a rigidbody of the traveling component 244 to form the pusher 242. Thetraveling component 244 is arranged to travel, linearly, along a linearactuation path 247 defined by the actuating component 248, to causelinear motion of the pushing component 246.

The pusher 242 may include a pusher interface (not shown). The pusherinterface may be arranged to engage with the at least a portion of thedistal end surface, such as the pusher interface 359 of FIG. 3D,disclosed further below. The pusher interface may include complementaryfeatures relative to surface features of the at least a portion of thedistal end surface of the rod of build material 204. For example, in anevent the at least a portion of the distal end surface is flat, thepusher interface may have a complementary feature, that is, a flatsurface. It should be understood that a flat surface is one example of asurface feature and that the at least a portion of the distal endsurface of the rod of build material 204 may have any suitable surfacefeatures and that pusher interface may include complementary featuresthat complement and correspond to such surface features.

According to an example embodiment, the pushing component 242 mayinclude at least one cantilevered protrusion of the traveling component244, such as the pushing component 242, that is, a cantileveredprotrusion in the example embodiment.

The pusher 242 may include a traveling component 244 arranged to causemotion of the pusher 242. According to an example embodiment, thetraveling component 244 may include a nut, such as the nut 245 of FIG.2E, disclosed further below.

According to an example embodiment, a linear guide, such as the linearrail 262, may be coupled to the traveling component 244 via a linearbearing 243. The linear bearing 243 may be any suitable linear bearing,such as a bushing or a ball bearing. The linear bearing 243 may bearranged to roll along the linear rail 262. The linear rail 262 may becoupled to an actuation assembly frame 249 of the actuation assembly208. The linear bearing 243, in combination with the linear rail 262,may be arranged to guide the traveling component 244 as the travelingcomponent 244 travels along the actuating component 248 and relieve aload otherwise applied to the actuating component 248 due to the axialforce 235 applied to the rod of build material 204 by the pushingcomponent 246. It should be understood that the linear guide need not bea linear rail and may be any other suitable linear guide.

FIG. 2B is a block diagram of an example embodiment of a distal endsurface 233 of the rod of build material 204 and the axial force 235. Asdisclosed above with regard to FIG. 2A, the axial force 235 may beapplied to at least a portion of the distal end surface 233. Accordingto an example embodiment, the axial force 235 may be applied along anaxis that is substantially parallel to a longitudinal axis 236 that runslengthwise along a length 237 of the build material 204. It should beunderstood that a shape of the rod of build material 204 may be of anysuitable shape, such as illustrated in FIG. 2C, disclosed below, or anyother suitable shape, and that the distal end surface 233 may have anysuitable surface features.

FIG. 2C is a block diagram of another example embodiment of across-sectional surface 233 of the rod of build material 204 and theaxial force 235.

FIG. 2D is a block diagram of an example embodiment of a 3D coordinatesystem and the axial force 235. The axial force 235 is substantiallyparallel to the z-axis 238 and is in a direction toward the extrusionhead 212.

FIG. 2E is a CAD drawing of a cross-sectional view of an exampleembodiment of the extrusion assembly 206 of FIG. 2A, disclosed above.According to the example embodiment, the actuating component 246 may bea lead screw and the traveling component 244 may include a nut 245coupled to the lead screw. The nut 245 coupled to the lead screw may bereferred to interchangeably herein as a lead screw nut. Further, thelead screw may be referred to as an actuating component or a linearactuating component.

In operation, as the driving component 252 drives the actuatingcomponent 246, the actuating component 246 is caused to rotate which, inturn, causes the traveling component 244 to move in a linear directionresulting in linear motion of the pushing component 246. With thepushing component 246 positioned in the slot 251, rotation of the nut245 relative to the lead screw, that is, the actuating component 246, isprevented, in the example embodiment.

According to the example embodiment, the extrusion assembly 206 mayfurther comprise a guide channel 241 (e.g., alignment device) thatdefines at least one slot, such as the slot 251. The guide channel 241may have a same length as a length of the rod of build material 204 ormay have a different length. In the example embodiment, the guidechannel 241 has a tubular structure, however, the guide channel 241 mayhave any suitable shape for guiding the rod of build material 204. Theguide channel 241 may be employed to prevent buckling of the buildmaterial 204. The guide channel 241 may or may not run a full length ofthe rod of build material 204. The extrusion assembly 206 may include amedia loading component 255 that defines an entrance 257 for the rod ofbuild material 204. In the example embodiment, the rod of build material204 is not present. According to an example embodiment, the medialoading component 255 may have a funnel shape, such as shown in FIG. 2F,disclosed below. However, it should be understood that the media loadingcomponent 255 need not have the funnel shape and may have any suitableshape for directing the rod of build material 204 into the extrusionassembly 206.

The at least a portion of the path the rod travels toward the extrusionhead 212 may be defined, in part, by the guide channel 241. The slot 251may be configured to receive the pushing component 246. The guidechannel 241 may be arranged to contact at least a portion of the rod ofbuild material to provide alignment for the at least a portion of therod.

FIG. 2F is a CAD drawing of another example embodiment of the extrusionassembly 206 of FIG. 2A, disclosed above. In the example embodiment, theactuating component 248 is a lead screw and the linear rail bearing 243and linear rail 262 are not employed. The extrusion assembly 206includes the guide channel 241 that defines the slot 251, disclosedabove with regard to FIG. 2E. The actuation assembly 208 furtherincludes a cam 250 arranged at a home location 227 for the pusher 242 toguide the pushing component 242 out of the way of a path the rod ofbuild material 204 travels toward the extrusion head 212 and moves thepushing component 246 into a media load position 263, as disclosed belowwith regard to FIG. 2G. The cam 250 may be any suitable component thatis arranged to cause movement of another component that it comes intocontact.

For example, the cam 250 may be arranged to cause the pushing component246 to exit the slot 251 of the guide channel 241 via the pushingcomponent entrance/exit 260. Following loading of the build material 204into the extrusion assembly 206, the driving component 258 may drive theactuation component to cause the pusher 242 to move downward in adirection toward the extrusion head 212 and the cam 250 may be arrangedto guide the pushing component 246 back into the slot 251 and above thedistal end 232 of the rod of build material 204, positioning the pushingcomponent 246 in an extrude position, such as disclosed below withregard to FIG. 2H. The driving component 252 may drive the actuatingcomponent to cause the pusher 242 to travel and the pushing component246 to apply the axial force 235, as disclosed above with regard to FIG.2A.

FIG. 2G is a CAD drawing of an example embodiment of the pushingcomponent 246 of FIG. 2F in a passive position to enable media loading.

FIG. 2H is a CAD drawing of an example embodiment of the pushingcomponent 246 of FIG. 2F in an active position for extruding media, thatis, the media extrude position 265.

FIG. 2I is a CAD drawing of a cross-sectional view of an exampleembodiment of the cam 250 of FIG. 2F, disclosed above. As illustrated inFIG. 2G and FIG. 2H, the cam 250 may be arranged to cause the pushingcomponent 246 to transition between a media load position and a mediaextrude position as a function of surface contact between the cam 250and the pushing component 246. In the media load position, the pushingcomponent may be arranged to be out of the path the rod travels towardthe extrusion head. In the media extrude position, at least a portion ofthe pushing component may be arranged to be in the path the rod travelstoward the extrusion head.

FIG. 2J is a block diagram of an example embodiment of a path the rod ofbuild material 204 may travel toward the extrusion head 212. Accordingto an example embodiment, the extrusion assembly may include a mediaentrance arranged to load the rod of build material into the extrusionassembly. The path the rod travels toward the extrusion head may be fromthe media entrance to the extrusion head. For example, the rod of buildmaterial may enter a media entrance of the extrusion assembly, such asthe media entrance M1 or the media entrance M2 in any suitable way andtravel from a starting location, such as S1 or S2, at the respectivemedia entrance to reach the extrusion head 212. The rod of buildmaterial 204 may enter along any axis and may be positioned into areload path 229 or directly into the extrusion path 238. Positioning ofthe pushing component 246 in either of the media reload position ormedia extrude position, such as disclosed above with regard to FIG. 2Gand FIG. 2H, may be based on the home location 227 of the pusher 242.The home location 227 may be a location of the extrusion assembly wherethe pusher 242 dwells during non-extrusion.

The rod of build material 204 may enter at the media entrance M1 andtravel the path P1 to reach the extrusion head 212. As such, the pushingcomponent 246 may be positioned in the media load position 263 when thepusher 242 is at the home location 327 so as not to block or hinder thepath P1. Alternatively, the home location 227 may be such that thepushing component 246 may remain in the media extrude position 265during media loading. For example, the home location 227 may be abovethe media entrance, such as the media entrance M2. As such, the pushingcomponent 246 may overlap the extrusion path 238 as media is loaded fromthe media entrance M2, since the pushing component 246 would not overlapthe path P2 traveled by the rod of build material to reach the extrusionhead 212 from the starting location S2 at the media entrance M2.

It should be understood that while the reload path 229 is shown in FIG.2J as linear, the reload path 229 may include paths that are linear,non-linear, or a combination thereof, as illustrated. According to anexample embodiment, the extrusion path 238 may be substantially linear.The reload path 229 may be referred to interchangeably herein as a loadpath.

In operation, following loading of the rod of build material 204, thedriving component 252 may be configured to drive the actuating component248 in a first direction to cause the pusher 242 to move from the homelocation 227 and move the rod of build material toward the extrusionhead 212. The driving component may be configured to drive the actuatingcomponent such that the actuating component is driven in a reversedirection in an event the pusher 242 moves to the reset location 226that is closer to the extrusion head relative to the home location 227.The reset location 226 may or may not be at the extrusion head 212.

Turning back to FIG. 2E, the driving component 252 may be an electricmotor (with or without gearbox) that may be set in-line with theactuating component 248, that is a lead screw in the example embodiment,to which a traveling component 244, such as a nut, may be attached. Thenut, that is, the traveling component 244 has a cantilevered protrusionin the example embodiment, that is, the pushing component 246, which canbe driven to contact and drive the feedstock, that is, a rod of buildmaterial, into the hotend 258 of the liquefying extruder, that is, theextrusion head 212.

The pusher 242 may have a piston-like motion of the actuation assembly208, that drives a rod of build material into the hotend 258. Inaddition, it may be useful to control an offset between the drivingcomponent 252, that may be a motor, and the media being driven into thehotend 258 in order to control a time response of the extrusion assembly206. The motor may be positioned as shown in the present orientation orin an alternate configuration opposite the hotend 258 (e.g., mirrorabout the assembly height). A pitch of the lead screw, that is, theactuating component 248, may be controlled to control the ability tofinely-tune the material flow through the hotend 258. A diameter andmaterial of the lead screw, that is, the actuating component 248,affects stiffness of the extrusion assembly system 206. By making thediameter larger, the stiffness may be increased. By selecting a materialwith a larger Young's modulus, the stiffness may be increased.

Turning back to FIG. 2F, according to an example embodiment of theextrusion assembly 206, the actuation assembly 208 may include the guidechannel 241, that may be a tube which confines the media and may preventthe media from buckling; a funnel 255 which directs the media as it isinserted into the confining tube 241; a nut 244 with an appendage 246 topush the media into the hotend 258; and a slot 260 in the confining tube241 which permits the nut 244 to rotate out of the way of the confiningtube 241 when a new rod is to be loaded, as shown in FIG. 2G, disclosedabove. In FIG. 2G, the nut 244 is rotated into the confining tube 241 topush the media.

According to an example embodiment, a rod of the build material may alsobe cooled actively or passively in the guide channel 241. The guidechannel 241 may also be outfitted with sensors to indicate the absoluteor relative positions of the rod. The nut 244 with appendage 246configured to push the media can also be combined with a strain gage toindicate a force on the media. According to a further exampleembodiment, the nut 244 with appendage 264 in combination form thepusher 242 to push the media and may be combined with a miniature loadcell to indicate a force on the media. The pushing component 246 as anappendage may be referred to interchangeably herein as a finger.

FIG. 3A is a CAD drawing of an example embodiment of a portion of anextrusion assembly 306. The actuation assembly 306 includes a pusher 342that includes a traveling component 344 and a pushing component 346. Thepushing component 346 is arranged to apply an axial force 335 to a rodof build material 304, such as disclosed above with regard to FIG. 2A.The actuation assembly includes a linear rail 362 coupled to a frame 349of the actuation assembly 208 and a linear bearing 343 arranged tocouple the traveling component 344 to the linear rail 362. The linearrail 362 in combination with the linear bearing 343 may be arranged toguide the traveling component 344 as the traveling component 344 travelsalong the actuating component 348 and relieve (e.g., absorb) a load,such as an axial load, otherwise applied to the actuating component 348due to the axial force 335 applied to the rod of build material 304 bythe pushing component 346, as disclosed above with regard to FIG. 2A.The pusher 342 may include a return spring 331 that may be arranged tomaintain pushing of the pushing component 346 relative to the travelingcomponent 344 and prevent rotation of the pushing component 346.

FIG. 3B is a CAD drawing of an isometric view of the example embodimentof FIG. 3A, disclosed above, that includes a guide tube 341. In theexample embodiment, there is contact 333 between the guide tube 341 andthe rod of build material 304. As such, the guide tube 341 isadvantageously arranged to maintain an alignment of the rod of buildmaterial 304 as the rod travels toward the extrusion head 312, inaddition to preventing buckling. The actuating component 348 may be alead screw, as disclosed above with regard to the extrusion assembly206, that may be driven by the driving component 352. The actuationassembly includes the linear rail 362 coupled to the frame 349 of theactuation assembly 208 and the linear bearing 343 arranged to couple thetraveling component 344 to the linear rail 362. The pusher includes areturn spring 331, as disclosed in FIG. 3C, below.

FIG. 3C is a CAD drawing of an isometric view of the pusher 342 of FIG.3A, disclosed above. The pusher 342 includes a cam 350 that is coupledto the traveling component 344 via a return spring 331 that may also bereferred to herein as a retract spring. The return spring 331 enablesthe pushing component 346 to be maintained as a rigid body within thetraveling component. The pushing component 346 is coupled to the cam 350at the pusher component/cam interface 336. In the example embodiment, inoperation, as the pusher 342 returns to a reload position, such as themedia load position 337, disclosed above, the pusher component/caminterface 336 makes contact with the guide channel retract cam 361 andthe pushing component 336 rotates downward about the y-axis, such as they-axis 239 of FIG. 2D, disclosed above, as the pusher 342 is moving inan upwards direction, that is, in the −z-axis direction 264 of FIG. 2D.As such, another rod of the build material 304 may be loaded into theextrusion assembly 306.

FIG. 3D is a CAD drawing of another isometric view of another exampleembodiment of the pusher 342 of FIG. 3A, disclosed above. In the exampleembodiment, the pusher 342 includes a preload mechanism 365 and apre-load compression spring 367. The pre-load mechanism 365 may beformed of plastic or any other suitable material and is configured toabut a surface of the build material 304 and apply a lateral force 371that works in combination with surface contact 373 of the build material304 with a surface of the guide channel 341 to align the rod of buildmaterial 304. The pre-load compression spring 367 may be configured tobias the pre-load mechanism 365.

FIG. 4A is a CAD drawing of an isometric view of an example embodimentof an extrusion assembly 406 that includes a linear rail (not visible)and a pushing component 446 with gears that is configured to pivot aboutthe y-axis. The pushing component 446 may be referred to interchangeablyherein as a geared flipper. The extrusion assembly 406 includes a linearrail 462 coupled to an actuation assembly frame 449 of the actuationassembly 408. The linear rail 462 may be coupled to the travelingcomponent 444 via the linear bearing 443. The linear bearing may bearranged to roll along the linear rail 462. The linear bearing maylocate the pusher 442 along the linear rail 462. The stiffness of thepusher 442 may be higher relative to a stiffness of the pusher 242,disclosed above. Enhancing the stiffness may be useful to reduce anamount of unwanted flow from the extrusion assembly 406, and also tominimize a delay in time between an instant in which a flow rate commandis sent and when the flowrate is realized at the nozzle tip.

Further, the traveling component 444 may be a nut on the actuatingcomponent 448 and the nut is confined not to rotate relative to theactuation component 448 that may be a lead screw. In addition, accordingto an example embodiment, the nut may be anti-backlash. According toanother example embodiment, the nut may be a split nut with a spring(i.e., anti-backlash nut).

Using a standard threaded nut which is cut and the twopartially-separated sides either forced together or apart provides abinding action between the lead screw and nut. Further, a nut onto whichan element which rotates is included. The element which rotates containsa through hole to permit the passage of the print media. In addition,the element which rotates contains an element to engage with a fixedelement actuating the rotation in at least one position in the device.The element which rotates may be spring loaded to remain in a preferredorientation during operation. The element which rotates may be thepushing component 446, as disclosed above with regard to FIG. 3C.

FIG. 4B is a cross sectional view of the example embodiment of theextrusion assembly 406 of FIG. 4A. The linear bearing 443 in combinationwith the linear rail 462 may be arranged to guide the travelingcomponent 444 as the traveling component 444 travels along the actuatingcomponent 448 and relieves a load otherwise applied to the actuatingcomponent 448 due to the axial force 435 applied to the rod of buildmaterial 404 by the pushing component 446 at a pusher/build materialinterface 468. The linear bearing 443 is arranged to position the pusher442 along the linear rail 462. The extrusion assembly 406 includes a cam450 located at the home position 427 of the pusher 442. In the exampleembodiment, the cam 450 performs similar to a rack and pinion. In theexample embodiment, the pushing component 446 and the cam 450 definecomplementary features, that is, the gear teeth 477.

FIG. 5 is a flow diagram 500 of an example embodiment of a method formoving a rod of build material in a three-dimensional (3D) printingsystem. The method may begin (502) and engage a rod of build material,loaded into an extrusion assembly including an extrusion head, with apusher, the rod having distal and proximal ends relative to theextrusion head, the distal and proximal ends having distal and proximalend surfaces, respectively (502). The method may apply an axial force toat least a portion of the distal end surface of the distal end of therod, the axial force being applied, by the pusher, to the at least aportion of the distal end surface for at least a portion of a path therod travels toward the extrusion head in the 3D printing system (506),and the method thereafter ends (508) in the example embodiment.

FIG. 6 is a block diagram of an example embodiment of an actuationsystem 680 for use in a three-dimensional (3D) printing system. Theactuation system 680 comprises a pusher 642, an actuating component 648coupled to the pusher 642; a driving component 252 configured to drivethe actuating component 648, and a controller 618. The controller 618may be configured to cause the driving component 252 to drive theactuating component 648 to move in a manner that causes the pusher 642to apply an axial force to at least a portion of a distal end surface ofa distal end of a rod of a build material. The rod may have distal andproximal ends relative to an extrusion head. The distal and proximalends may have distal and proximal end surfaces, respectively. The axialforce may be applied to the at least a portion of the distal end surfaceof the rod for at least a portion of a path the rod travels toward theextrusion head in the 3D printing system, such as the 3D printing system100 of FIG. 1, disclosed above.

The actuation system 680 may further comprise a sensor 617. The sensor617 may be any suitable sensor(s), such as an optical, capacitive, ormechanical sensor that may provide feedback to the controller 618enabling the controller 618 to track location of the rod of buildmaterial 204. For example, the sensor 617 may enable the controller 618to monitor drive current of the driving component 252 and determinelocation based on the current. Alternatively, the sensor 617 may not beemployed and the controller may track location of the rod of buildmaterial 204 in an open-loop manner as a function of a theoreticalcommanded location. For example, according to an example embodiment, thedriving component 252 may be a stepper motor and the controller 618 maytrack location of the rod based on a number of counts of the steppermotor and a direction of actuation commanded on the actuating component648. It should be understood that the driving component 252 may be anysuitable driving component for driving actuation of the actuatingcomponent 648 in multiple directions, such as reverse and forward.Further, the controller 618 may track location of the rod by trackingcommands issued to components of the actuation system 680 and optionallybased on time. Regardless of whether such tracking is performed withfeedback or in an open-loop manner, such tracking may enable theactuation system 680 to be an automated system the loads and extrudesrods of build material for 3D printing, automatically.

According to an example embodiment, an extrusion assembly for use in athree-dimensional (3D) printing system may include an extrusion headconfigured to receive a build material and an actuation assembly. Theactuation assembly may include an actuating component and a gripper. Thegripper may be arranged to apply at least two opposing lateral forces tothe build material, the at least two opposing lateral forces beingapplied to the build material for at least a portion of a path the buildmaterial travels toward the extrusion head. The actuating component maybe arranged to cause linear motion of the gripper for the at least aportion of the path.

The at least two opposing lateral forces, in combination with the linearmotion, cause corresponding shear forces to be applied to the buildmaterial. The shear forces correspond to the at least two lateralforces.

The build material 204 for use with the gripper may be in a form of adiscrete rod or continuous feedstock.

According to an example embodiment, the gripper may be arranged to applythe at least two lateral forces via vacuum. Alternatively, such forcesmay be applied via pneumatics or in any other suitable way.

As the at least two opposing lateral forces are being applied to thebuild material, for the at least a portion of a path the build materialtravels toward the extrusion head, the gripper is moving linearly alongwith the build material since the actuating component is arranged tocause linear motion of the gripper for the at least a portion of thepath. Further, according to an example embodiment, the at least twolateral forces may be sufficient to overcome extrusion forces. A surfacearea for contact of the build material may be configured such that theat least two lateral forces do not deform the build material, forexample, by indenting the build material otherwise caused by individualcontact points, such as teeth. According to an example embodiment, theat least two lateral forces may be distributed such that the buildmaterial maintains structure in an area over which such lateral forcesare applied.

FIG. 7 is a flow diagram 700 of an example embodiment of another methodfor moving a rod of build material using a gripper in athree-dimensional (3D) printing system. The method begins (702) andapplies at least two opposing lateral forces to a build material via agripper, the at least two opposing lateral forces being applied to thebuild material for at least a portion of a path the build materialtravels toward an extrusion head (704). The method causes linear motionof the gripper for the at least a portion of the path the build materialtravels toward the extrusion head (706), and the method thereafter ends(708), in the example embodiment.

FIG. 8 is a block diagram of an example embodiment of an actuationsystem 880 that uses a gripper 872. The actuation system 880 comprisesthe gripper 872 that is coupled to a traveling component 844, anactuating component 848 that is coupled to the traveling component 844;a driving component 852 that may be configured to drive the actuatingcomponent 848; and a controller 818 that may be configured to activateand deactivate the driving component 852.

The driving component 852 may be further configured to drive theactuating component 848 to cause the traveling component 844 to movebi-directionally relative to an extrusion head (not shown).

The actuation system 880 may further comprise a sensor 817. The sensor817 may be any suitable sensor(s), such as an optical, capacitive, ormechanical sensor that may provide feedback to the controller 818enabling the controller 818 to track location of build material 204. Forexample, the sensor 817 may enable the controller 818 to monitor drivecurrent of the driving component 852 and determine location based on thecurrent. Alternatively, the sensor 817 may not be employed and thecontroller may track location of the rod of build material 204 in anopen-loop manner as a function of a theoretical commanded location.

FIG. 9A is a cross sectional view of an example embodiment of anextrusion assembly 906 that includes an actuation assembly 908 in astart mode. The actuation assembly 908 includes an actuating component848 and a gripper 972. The gripper 972 is arranged to apply at least twoopposing lateral forces (not shown) to the build material 904. The atleast two opposing lateral forces are applied to the build material 904for at least a portion of a path the build material 104 travels towardan extrusion head 912. The actuating component 948 is arranged to causelinear motion of the gripper 972 for the at least a portion of the path.For example, the gripper 972 is arranged to apply the at least twoopposing lateral forces while in the extrusion zone 982 as the gripper972 is caused to travel linearly through the extrusion zone 982 towardthe extrusion head 912.

In the example embodiment, the actuating component 948 is a captivemotor. The actuation assembly further includes a traveling component944, that is, a lead screw through the captive motor that is hollow,permitting the media to pass through its hollow core 974. In the exampleembodiment, the gripper is a collet. The lead screw is attached to thecollet which normally operates in an open position, such that the media,that is, the build material 904, is not pinched or engaged. The leadscrew, that is, the traveling component 944, may be attached to thegripper 972 in any suitable way, such as via a gripper coupling 976. Thehotend 958 is located in a plane beneath a plane of the captive motor,in the example embodiment. A gripper guide 941, that is, a cam tube inthe example embodiment, sits in-between the captive motor and the hotend958. In normal operation, a rod of build material 904 to be extruded isdropped into the cam shaft between the hotend 958 and the motor, thatis, the driving component 952.

To drive the build material 904 into the hotend, the motor is actuatedto drive the lead screw and collet, that is, the traveling component 944and the gripper 972, toward the build material 904, which is a rod ofbuild material in the example embodiment, and push the gripper 972toward the extrusion head because the gripper 972 is attached to thetraveling component 944. Once the gripper 972 reaches the gripper guide941 and enters, that is, the collet reaches the cam, the cam squeezesinward onto the feedstock and engages the feedstock such that the axialmotion of the feedstock is now constrained to the axial motion of thecam and lead screw, which can be toward or away from the hotend 958(provided motion away from the hotend 958 does not pull the collet outof the cam tube). For example, the gripper guide 941 may define a guideshaft 779 that has a profile causing the gripper 972 to constrict ordilate, imposing and releasing at least two opposing lateral forces onthe build material 904.

Once the build material 904 has been pushed completely through thehotend 958, the collet continues forward to the hotend 958 until thebuild material 904 is released as the collet leaves the proximal end 981of the cam tube, the proximal end 981 being closer to the extrusion head912 relative to the distal end 983. Once the collet leaves the cam tube,it is withdrawn back toward the motor by reversing the direction ofrotation on the lead screw. Since the force required to collapse thecollet is smaller than the force on the cam tube, the cam tube is drivenback toward the motor engaging a spring 984. Once the spring forceexceeds the force required to collapse the collet (or the cam bottomsout), the collet once again enters the cam tube, that is, the gripperguide 941, and is driven back toward the original position. At thispoint, a new rod may be loaded and the collet driven back toward the rodof build material 904 to begin the extrusion process again.

FIG. 9B is a cross sectional view of an example embodiment of theextrusion assembly FIG. 9A with the actuation assembly transitioned toan extrusion mode. As illustrated in FIG. 9B, the gripper guide 941defines a distal zone 987, extrusion zone 982, and proximal zone 986.The proximal zone 986 is closer to the extrusion head 917 relative tothe distal zone. An inner surface profile of the gripper guide 941 issuch that the gripper 972 is configured to be open (e.g., dilated) inthe distal and proximal zones and compressed (e.g., constricted) in theextrusion zone 982 so as to grip the build material 904 by applying atleast two lateral forces. In the example embodiment of FIG. 9B, thegripper 972 is clamped and the build material 904 may be extruded orretracted, whereas in FIG. 9A the gripper 972 is open with no hold onthe build material 904.

FIG. 9C is a cross sectional view of an example embodiment of theextrusion assembly of FIG. 9A with the actuation assembly transitionedto a first media reload mode in which the gripper 972 opens and thedriving component 952 reverses direction.

FIG. 9D is a cross sectional view of an example embodiment of theextrusion assembly of FIG. 9A with the actuation assembly transitionedto a second media reload mode in which the driving component 952reverses, causing the gripper 972 to reverse up and into the gripperguide 941 and the gripper guide 941 slides in a direction away from theextrusion head to be above the build material 904 before the gripper 972is caused to closed.

FIG. 9E is a cross sectional view of an example embodiment of theextrusion assembly of FIG. 9A with the actuation assembly transitionedto a third media reload mode in which the gripper guide 941 bottoms out,the gripper 972 closes, and the gripper rides to the top. Once thegripper 972 reaches an open part of the gripper guide, the gripper 972opens and the gripper guide 941 springs back the down position as shownin FIG. 9A.

In the example embodiment of FIG. 9E, a telescoping media guide 998 iscoupled to the gripper 972. The telescoping media guide 998 is optionaland may be employed, for example, to ensure that hold on the buildmaterial 904 is maintained in an event the extrusion zone 982 is long.The telescoping media guide 998 may be a spring or any other suitablecompliant element.

The actuation assembly 908 may further include a gripper guide 941, thegripper 941 guide arranged to cause the gripper 941 to apply the atleast two opposing lateral forces (not shown). The actuation assemblymay further include a spring 984 arranged to cause the gripper guide 941to move in a direction away from the extrusion head 912 and toward ahome position 927 for the gripper guide 941 within the actuationassembly 908.

The extrusion assembly may include an extrusion frame 991 arranged tohouse the gripper 972, a gripper guide 941 for the gripper 972, and aspring 984.

The extrusion frame 991 may define a stopping ledge 992 within the frame991, the stopping ledge 992 arranged to stop movement of the gripperguide 941 in a direction away from the extrusion head 912. The stoppingledge 992 may define the home position 927 for the gripping guide 941and the gripper 972.

The extrusion assembly 906 may further comprise a traveling component944, as disclosed above. The gripper 972 may be coupled to the travelingcomponent 944 and the actuation assembly 908 may further include: thegripper guide 941 arranged to cause the gripper 972 to dilate andcontract within the gripper guide 941 and a driving component 952configured to drive the actuating component 948 to cause the travelingcomponent 944 to move bi-directionally relative to the extrusion head912.

The traveling component 944 may define a hollow core 974 configured toenable the build material to pass through the traveling component 944and toward the extrusion head 912, as disclosed above.

According to another example embodiment, a linear motor may drive themedia into the hotend. A linear motor such configured has no rotatingcomponents and may be placed adjacent to the media to be extruded. Thelinear motor may have a pushing mechanism similar to the gear-typepusher shown in connection with FIGS. 4A and 4B, or the collet typepusher as show in connection with FIGS. 9A-E, or a gated pushingmechanism which may be actuated in and out.

It should be understood that various example embodiments of an extrusionassembly may be shown in figures as being oriented directly in-line withthe nozzle tip on a build plate, such as the build plate 120 of FIG. 1,disclosed above. However, this need not be the case. An extrusionassembly as disclosed herein may be oriented at any angle off-axis whichmay advantageously reduce an amount head space required within the 3Dprinting system.

FIG. 10A is block diagram of an example embodiment of a gripper 1072.According to the example embodiment, an actuation assembly (not shown)further comprises a first 993 a belt and a second belt 993 b and thebuild material 1004 may be arranged between surfaces of the first beltand second belts.

The gripper 1072 may be coupled to the first belt 993 a and the secondbelt 993 b and arranged to apply the at least two lateral forces to thebuild material 1004 via the first and second belts. For example, anactuating component, such as the actuating component 1048 of FIG. 10Bmay cause lateral movement of at least one gripper element causing theat least one gripper element to contact a respective belt and apply alateral force to the build material 1004. According to an exampleembodiment, at least one of the gripper elements may be fixed to arespective belt applying at least one lateral force. As such, to movethe build material 1004 toward the extrusion head 1010, the actuatingcomponent 1048 may be driven in manner that causes a second gripperelement to apply at least one second lateral force that opposes thelateral force applied by the first gripping element.

FIG. 10B is block diagram of an example embodiment of the gripper ofFIG. 10A.

FIG. 11 is block diagram of another example embodiment of a gripper 1172and a gripper guide 1141. The gripper 1172 may include: a linear element1194; a first rolling element 1195 a; a second rolling element 1195 b; afirst gripping element 1196 a; and a second gripping element 1196 b. Thelinear element 1194 may be coupled to the first and second grippingelements and the at least two rolling elements.

The extrusion assembly may further comprise a linear guide 1162 and thegripper 1172 may be arranged to travel the linear guide 1162.

The linear motion of the gripper 1172 may cause the gripper 1172 toenter a gripper guide 1141 that may compressing and dilate the grippervia a profile of an internal surface of the guide 1141, such as aprofile of a path of travel by the rolling elements along the profilethat may cause gripping elements of the gripper 1172 to move in a mannerthat applies and removes the at least two lateral forces.

FIG. 12 is a block diagram of an example of the internal structure of acomputer 1200 in which various embodiments of the present disclosure maybe implemented. The computer 1200 contains a system bus 1202, where abus is a set of hardware lines used for data transfer among thecomponents of a computer or processing system. The system bus 1202 isessentially a shared conduit that connects different elements of acomputer system (e.g., processor, disk storage, memory, input/outputports, network ports, etc.) that enables the transfer of informationbetween the elements. Coupled to the system bus 1202 is an I/O deviceinterface 1204 for connecting various input and output devices (e.g.,keyboard, mouse, displays, printers, speakers, etc.) to the computer1200. A network interface 1206 allows the computer 1200 to connect tovarious other devices attached to a network. Memory 1208 providesvolatile storage for computer software instructions 1210 and data 1212that may be used to implement embodiments of the present disclosure.Disk storage 1214 provides non-volatile storage for computer softwareinstructions 1210 and data 1212 that may be used to implementembodiments of the present disclosure. A central processor unit 1218 isalso coupled to the system bus 1202 and provides for the execution ofcomputer instructions.

Further example embodiments disclosed herein may be configured using acomputer program product; for example, controls may be programmed insoftware for implementing example embodiments. Further exampleembodiments may include a non-transitory computer-readable mediumcontaining instructions that may be executed by a processor, and, whenloaded and executed, cause the processor to complete methods describedherein. It should be understood that elements of the block and flowdiagrams may be implemented in software or hardware, such as via one ormore arrangements of circuitry of FIG. 12, disclosed above, orequivalents thereof, firmware, a combination thereof, or other similarimplementation determined in the future. In addition, the elements ofthe block and flow diagrams described herein may be combined or dividedin any manner in software, hardware, or firmware. If implemented insoftware, the software may be written in any language that can supportthe example embodiments disclosed herein. The software may be stored inany form of computer readable medium, such as random access memory(RAM), read only memory (ROM), compact disk read-only memory (CD-ROM),and so forth. In operation, a general purpose or application-specificprocessor or processing core loads and executes software in a mannerwell understood in the art. It should be understood further that theblock and flow diagrams may include more or fewer elements, be arrangedor oriented differently, or be represented differently. It should beunderstood that implementation may dictate the block, flow, and/ornetwork diagrams and the number of block and flow diagrams illustratingthe execution of embodiments disclosed herein. Further, exampleembodiments and elements thereof may be combined in a manner notexplicitly disclosed herein.

While example embodiments have been particularly shown and described, itwill be understood by those skilled in the art that various changes inform and details may be made therein without departing from the scope ofthe embodiments encompassed by the appended claims.

What is claimed is:
 1. An assembly for use in an additive manufacturingsystem, the assembly comprising: an extrusion head configured to receivea rod of build material along a longitudinal axis of the extrusion head;and an actuator movable relative to the extrusion head along an axisextending parallel to the longitudinal axis, a pushing component of theactuator configured to exert a force on a distal end of the rod of buildmaterial along the longitudinal axis toward the extrusion head, whereinthe actuator is configured to swivel or pivot between a firstconfiguration, in which the pushing component intersects thelongitudinal axis for exerting said force, and a second configurationemployed for loading the rod of build material into the assembly alongthe longitudinal axis, in which the pushing component does not intersectthe longitudinal axis.
 2. The assembly of claim 1, wherein the actuatorincludes a body and a protrusion of the pushing component extendingoutwardly from the body, wherein the protrusion intersects thelongitudinal axis in the first configuration, and wherein the protrusiondoes not intersect the longitudinal axis in the second configuration. 3.The assembly of claim 1, further comprising a cam configured totransition the actuator from the first configuration to the secondconfiguration.
 4. The assembly of claim 3, wherein an interactionbetween a surface of the cam and a surface of the actuator causes theactuator to transition from the first configuration to the secondconfiguration.
 5. The assembly of claim 1, further comprising a guidechannel configured to receive the rod of build material, wherein theguide channel defines a slot that is configured to receive at least aportion of the actuator.
 6. The assembly of claim 5, wherein, in thefirst configuration, the at least the portion of the actuator isreceived by the slot, and wherein, in the second configuration, the atleast the portion of the actuator is not received by the slot.
 7. Theassembly of claim 1, wherein the actuator includes a body and aprotrusion of the pushing component extending outwardly from the body,and wherein the protrusion includes an interface surface configured tocontact the rod of build material.
 8. The assembly of claim 7, whereinthe interface surface is configured to exert the force on the rod ofbuild material when the actuator moves in a first direction toward theextrusion head, and wherein a surface of the body extends further in thefirst direction than the interface surface.
 9. An assembly for use in anadditive manufacturing system, the assembly comprising: an extrusionhead configured to receive a rod of build material along a first axis;an actuator movable along a second axis extending parallel to the firstaxis from a first position to a second position and from the secondposition to the first position, wherein the actuator is closer to theextrusion head in the first position than in the second position, andwherein a pushing component of the actuator is configured to exert aforce on a distal end of the rod of build material along the first axistoward the extrusion head; and a cam configured to interact with theactuator as the actuator moves from the first position to the secondposition to cause the pushing component to move in a directiontransverse to the first axis to a configuration employed for loading therod of build material into the assembly along the first axis.
 10. Theassembly of claim 9, wherein the actuator includes a body and aprotrusion of the pushing component extending outwardly from the body,and wherein the cam is configured to interact with the actuator as theactuator moves from the first position to the second position to causethe protrusion to move in the direction transverse to the first axis.11. The assembly of claim 9, wherein when the cam interacts with theactuator as the actuator moves from the first position to the secondposition, the actuator transitions from a first configuration, in whichthe pushing component intersects the first axis for exerting said force,to a second configuration in the direction transverse to the first axis,in which the pushing component does not intersect the first axis. 12.The assembly of claim 9, further comprising a guide channel configuredto receive the rod of build material, wherein the guide channel definesa slot that is configured to receive at least a portion of the actuator.13. The assembly of claim 12, wherein, in a first configuration in whichthe pushing component is configured to exert said force, the at leastthe portion of the actuator is received by the slot, and wherein, in asecond configuration employed for said loading of the rod of buildmaterial, the at least the portion of the actuator is not received bythe slot.
 14. The assembly of claim 9, wherein the actuator includes abody and a protrusion of the pushing component extending outwardly fromthe body, and wherein the protrusion includes an interface surfaceconfigured to contact the rod of build material.
 15. The assembly ofclaim 14, wherein the interface surface is configured to exert the forceon the rod of build material when the actuator moves in a firstdirection toward the first position, and wherein a surface of the bodyextends further in the first direction than the interface surface. 16.An assembly for use in an additive manufacturing system, the assemblycomprising: an extrusion head configured to receive a rod of buildmaterial along a longitudinal axis of the extrusion head; and anactuator movable relative to the extrusion head along an axis extendingparallel to the longitudinal axis by a linear actuating component,wherein the actuator includes a body and a protrusion extendingoutwardly from the body, wherein a surface of the protrusion isconfigured to exert a force on a distal end of the rod of build materialalong the longitudinal axis toward the extrusion head, and wherein theprotrusion is configured to move relative to the body in a directiontransverse to the longitudinal axis to a configuration employed forloading the rod of build material into the assembly along thelongitudinal axis.
 17. The assembly of claim 16, further including acam, wherein the cam is configured to cause the protrusion to moverelative to the body in the direction transverse to the longitudinalaxis.
 18. The assembly of claim 16, further comprising a guide channelconfigured to receive the rod of build material, wherein the guidechannel defines a slot that is configured to receive at least a portionof the actuator.
 19. The assembly of claim 18, wherein, when theprotrusion moves relative to the body in the direction transverse to thelongitudinal axis, the protrusion transitions from a first configurationto a second configuration employed for said loading of the rod of buildmaterial, wherein, in the first configuration, the at least the portionof the actuator is received by the slot, and wherein, in the secondconfiguration, the at least the portion of the actuator is not receivedby the slot.
 20. The assembly of claim 16, wherein the surface of theprotrusion is configured to exert the force on the rod of the buildmaterial when the actuator moves the protrusion in a first directionalong the longitudinal axis toward the extrusion head, and wherein asurface of the body extends further in the first direction than thesurface of the protrusion.